In this paper I examine the thought of two late Ming Confucian thinkers, Qian Yiben（銭一本、1539─1610）and Sun Shenxing（孫慎行、1565─1636）, who are usually assigned to the so-called Donglin（東林）school. Their thought can be seen as a precedent of the unique Confucian theory of Chen Que（陳確、1604─1677）, who was active in the mid-seventeenth century, during the Ming-Qing transition. Chen asserted that human nature, the substance of human mind, should be understood as a body of potentiality, and that its content could be recognized only after it is fully unfolded through human efforts. He rejected the mainstream ‘original sage’（本来聖人）theory, which was popular among Confucian scholars during the whole pre-modern era of Chinese history. Although Qian and Sun essentially attached themselves to the ‘original sage’ theory, because of their fears concerning the problems brought about by an extreme version of that view, they formulated new ideas that were somewhat contradictory to it. Both Qian and Sun strongly emphasized the need to accomplish human nature by broadening and fulfilling the ‘four sprouts of virtue’（拡充四端）. Qian even proposes that human nature could become perfect only through human effort（人成性）, and Sun separates Confucian virtue（德）from human nature（性）. In this way, their thought can be considered a historical precedent of Chen Que’s denial of ‘original sage’ theory.